Optical recording media of the magneto-optical and phase change types are typically manufactured by depositing various recording layer-forming materials on substrates directly or through an undercoat layer by sputtering or evaporation. The substrates are often formed of resins, typically polymethyl methacrylate and polycarbonate, but these resins are less satisfactory in optical characteristics and water absorption.
JP-A 26024/1985 and 223341/1991 disclose the use of cyclic polyolefin of norbornenes and/or fused nonbornenes, for example, norbornene, tetracyclododecene and the like. It is a useful substrate material because of improved optical characteristics and minimal water absorption.
We have found that cyclic polyolefin substrates are still insufficient in adhesion to a recording layer or an undercoat layer which is applied thereon by a gas phase deposition method. During storage in a high temperature, high humidity environment, the overlying layers (recording or undercoat layers) can separate from the substrates.
Write-once or recordable optical recording disks of the type having recording and reflective layers on a substrate were proposed in accordance with the compact disk (generally known as CD) standard. See Nikkei Electronics, Jan. 23, 1989, No. 465, page 107; the Functional Dye Department of the Kinki Chemical Society, Mar. 3, 1989, Osaka Science & Technology Center; and SPIE, Vol. 1078, Optical Data Storage Topical Meeting, 80, 1989.
This type of disk generally has a dye layer, a reflective Au layer, and a protective layer disposed on a transparent resin substrate in this order. That is, the reflective layer is in close contact with the dye layer. As opposed to the prior art disk of the air sandwich structure wherein an air layer is provided on a dye layer of the disk in order to allow pits to be formed in the dye layer, the newly proposed disk is of the close contact type wherein the reflective layer is close to the dye layer. The close contact type configuration could meet the total disk thickness of 1.2 mm required by the CD standard. As to the substrates of these disks, the same problems as previously mentioned are recognized.
For the purpose of improving the resin flow during injection molding, that is, moldability, it appears effective to add a lubricant to the cyclic polyolefin of formula (I') in our copending application. However, if conventional lubricants such as ester, resin acid, and resinate amide lubricants are added to the cyclic polyolefins, the lubricants evolve gases during molding to introduce unevenness in the molded substrates and it becomes difficult to smoothly apply a dye layer on the substrates.